to know how? old u have to be get one.. and if my parent can sign for me

credit cards are not the only way to build credit but at your age it is not legal for a company to go into a contract with you. You have to be at the minimum 18 years old. Now if I was you and you really want a credit card I will call different companies and find out about a secure credit card this is where you give them a deposit of 200 dollars and you will use that money and you can't go over the amount you sent them and your minimum payment is 20 dollars. Now this is good because they report to the credit companies as if it was a regular credit card and they don't tell them it is a secure credit card. Now that is how I started building credit but I was over 18 and I know myself I was very bad with money so I did not want to owe anyone but once again I don't know if they will do it for someone who is a minor.